We usually require palatal expansion for the correction of skeletal transversal discrepancies with the combination of orthodontic and orthopedic movements. Rapid maxillary expansion (disjunction) is done to increase the transversal dimension to correct skeletal cross bites, and at the same time, to increase dental arch length. Rapid maxillary expansion , is indicated when the expansion necessities are greater than 4 mm or 5 mm and when the origin of the discrepancy is skeletal. The objective of Rapid maxillary expansion is to reduce orthodontic movements and undesired inclinations. forces that range between 2kg to 5kg per activation, in contrast with slow expansion that generates forces that range between 450 g and 900 g that may be insufficient to separate a mature midpalatal suture . Rapid maxillary expansion is obtained in 10 to 30 days, but the expander must remain in the mouth during six months to allow new bone to form in the suture I. Effects on the maxillary complex II. Effects on the alveolar processe III. Dental effects a) The disjunction provokes the opening of a distema between the central incisors. This diastema closes in 2 to 4 weeks due to the reciprocal traction of the transeptal fibers that connect the central incisors, thus producing an increase of arch length

1. Effects of Disjunction
( indication and contraindication)
ACHIEVED BY: Dr.Maen Dawodi

2. disjunction
• We usually require palatal expansion for the correction of skeletal transversal
discrepancies with the combination of orthodontic and orthopedic movements.
• Rapid maxillary expansion (disjunction) is done to increase the transversal
dimension to correct skeletal cross bites, and at the same time, to increase dental
arch length.

3. • Rapid maxillary expansion , is indicated
when the expansion necessities are greater
than 4 mm or 5 mm and when the origin of
the discrepancy is skeletal.
• The objective of Rapid maxillary expansion is
to reduce orthodontic movements and
undesired inclinations.

4. Rapid maxillary expansion requires activations
• forces that range between 2kg to 5kg per activation, in contrast with slow
expansion that generates forces that range between 450 g and 900 g that may
be insufficient to separate a mature midpalatal suture .
• Rapid maxillary expansion is obtained in 10 to 30 days, but the expander must
remain in the mouth during six months to allow new bone to form in the suture

5. Effects of disjunction
• I. Effects on the maxillary complex
• II. Effects on the alveolar processe
• III. Dental effects

6. Dental effects
• a) The disjunction provokes the opening of a distema between the central
incisors. This diastema closes in 2 to 4 weeks due to the reciprocal traction of
the transeptal fibers that connect the central incisors, thus producing an
increase of arch length

7. • B) The transeptal periodontal fibers unite the crowns of the incisors rapidly, and
the roots converge in only four months.
• C) A slight extrusion and palatinization of the central incisors can be observed.
It is believed that the palatinization is caused by the stretching of the perioral
muscles.

8. Disjunction indications
• 1. It is done in patients whose maxillary suture system has not fully matured.
• 2. Unilateral or bilateral skeletal cross bites.

9. Disjunction indications
• 3. Posterior dentoalveolar cross bites.
• 4. Patients in the early permanent and mixed dentition between 8 and 15 years
of age.

10. contraindication
• 1. Non-cooperative patients.
• 2. Open bite cases.
• 3. Dolichofacial or hyper-divergent patients.
• 4. Patients with skeletal maxillary or mandibular asymmetries.
• 5. Buccaly inclined molars

11. Thanks

12. Reference
• - 1001 tips in Orthodontics and its secrets OCR2 -2 ch6 page 185